I want first fragment to observe information via LiveData comming from second fragment. I tried doing the same but only in 1 Fragment and it worked, but as soon as I want to recieve the data in other fragment it stops working (textView has no text). How should I fix this problem?
SharedViewModel:
class SharedViewModel : ViewModel() {
private val selected : MutableLiveData<Person> = MutableLiveData<Person>()
fun select(person: Person){
selected.value = person
}
fun getSelected(): LiveData<Person>{
return selected
}
}
First fragment:
class FirstFragment : Fragment() {
private lateinit var sharedViewModel: SharedViewModel
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
sharedViewModel =
ViewModelProviders.of(this).get(SharedViewModel::class.java)
val root = inflater.inflate(R.layout.fragment_home, container, false)
val textView: TextView = root.findViewById(R.id.text_home)
sharedViewModel.getSelected().observe(viewLifecycleOwner, Observer{
textView.text = it.name
})
return root
}
}
Second Fragment:
class SecondFragment : Fragment() {
private lateinit var sharedViewModel: SharedViewModel
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
sharedViewModel =
ViewModelProviders.of(this).get(SharedViewModel::class.java)
val root = inflater.inflate(R.layout.fragment_dashboard, container, false)
val textView: TextView = root.findViewById(R.id.text_dashboard)
val person = Person("John")
val newPerson = Person("Anton")
val button2: Button = root.findViewById(R.id.button2)
val button: Button = root.findViewById(R.id.button)
button2.setOnClickListener {
sharedViewModel.select(person)
}
button.setOnClickListener {
sharedViewModel.select(newPerson)
}
return root
}
}
Class Person:
class Person (var name: String) {
}
I think you are using https://developer.android.com/reference/android/arch/lifecycle/ViewModelProviders#of(android.support.v4.app.Fragment) but instead you should be using https://developer.android.com/reference/android/arch/lifecycle/ViewModelProviders#of(android.support.v4.app.FragmentActivity). That's how sharing works.
Related
I have two fragments that share information with each other, in the first one I have an edit text and button widget. The second fragment is just a listview. When the user clicks the button, it displays whatever is in the edit text widget in the second fragment.
So if the user enters the text study and clicks the button the second fragment will display
Study
If the user then enters the text eat and clicks the button, the second fragment will display
Study
Eat
I am having so issues with displaying the texts
So far this is what I have done
class FirstFragment : Fragment() {
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
viewModel = activity?.run { ViewModelProvider(this)[MyViewModel::class.java]
} ?: throw Exception("Invalid Activity")
val view = inflater.inflate(R.layout.one_fragment, container, false)
val button = view.findViewById<Button>(R.id.vbutton)
val value = view.findViewById<EditText>(R.id.textView)
button.setOnClickListener {
}
return view;
}
}
class SecondFragment : Fragment() {
lateinit var viewModel: MyViewModel
#SuppressLint("MissingInflatedId")
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
viewModel = activity?.run { ViewModelProvider(this)[MyViewModel::class.java]
} ?: throw Exception("Invalid Activity")
val view = inflater.inflate(R.layout.page3_fragment, container, false)
val valueView = v.findViewById<TextView>(R.id.textView)
return view
The problem I am having is how to display the texts
If I undestand you correctly, you want to share data between fragments? If yes, you can do that with "shared" viewModel. For example:
class FirstFragment : Fragment() {
private var _binding: FragmentFirstBinding? = null
private val binding get() = _binding!!
private val sharedViewModel by activityViewModels<SharedViewModel>()
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View {
_binding = FragmentFirstBinding.inflate(inflater, container, false)
binding.buttonChangeFragment.setOnClickListener {
/*
You can change data here, or in navigateWithNavController() from
activity (You already have an instance of your viewModel in activity)
*/
sharedViewModel.changeData(binding.myEditText.text.toString())
if (requireActivity() is YourActivity)
(requireActivity() as YourActivity).navigateWithNavController()
}
return binding.root
}
}
class SecondFragment : Fragment() {
private var _binding: FragmentSecondBinding? = null
private val binding get() = _binding!!
private val sharedViewModel by activityViewModels<SharedViewModel>()
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View {
_binding = FragmentSecondBinding.inflate(inflater, container, false)
binding.secondFragmentText.text = sharedViewModel.someData.value
return binding.root
}
}
and your activity:
class YourActivity: AppCompatActivity() {
private lateinit var binding: YourActivityBinding
private lateinit var appBarConfiguration: AppBarConfiguration
private val sharedViewModel: SharedViewModel by lazy {
ViewModelProvider(
this
)[SharedViewModel::class.java]
}
private lateinit var navController: NavController
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = YourActivityBinding.inflate(LayoutInflater.from(this))
setContentView(binding.root)
navController = this.findNavController(R.id.nav_host_fragment)
appBarConfiguration = AppBarConfiguration(navController.graph)
}
/*
This function is just for test
*/
fun navigateWithNavController() {
navController.navigate(R.id.secondFragment)
}
override fun onSupportNavigateUp(): Boolean {
return NavigationUI.navigateUp(navController, appBarConfiguration)
}
}
And your viewModel should look something like this:
class SharedViewModel : ViewModel() {
private val _someData = MutableLiveData("")
val someData: LiveData<String>
get() = _someData
fun changeData(newData: String?) {
_someData.value = newData ?: _someData.value
}
}
Your view model should have a backing list of the entered words. When a word is added, the list can be updated, and in turn you can update a LiveData that publishes the latest version of the list.
class MyViewModel: ViewModel() {
private val backingEntryList = mutableListOf<String>()
private val _entryListLiveData = MutableLiveData("")
val entryListLiveData : LiveData<String> get() = _entryListLiveData
fun addEntry(word: String) {
backingEntryList += word
_entryListLiveData.value = backingEntryList.toList() // use toList() to to get a safe copy
}
}
Your way of creating the shared view model is the hard way. The easy way is by using by activityViewModels().
I also suggest using the Fragment constructor that takes a layout argument, and then setting things up in onViewCreated instead of onCreateView. It's less boilerplate code to accomplish the same thing.
In the first fragment, you can add words when the button's clicked:
class FirstFragment : Fragment(R.layout.one_fragment) {
private val viewModel by activityViewModels<MyViewModel>()
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
val button = view.findViewById<Button>(R.id.vbutton)
val value = view.findViewById<EditText>(R.id.textView)
button.setOnClickListener {
viewModel.addEntry(value.text.toString())
}
}
}
In the second fragment, you observe the live data:
class SecondFragment : Fragment(R.layout.page3_fragment) {
private val viewModel by activityViewModels<MyViewModel>()
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
val valueView = view.findViewById<TextView>(R.id.textView)
viewModel.entryListLiveData.observe(viewLifecycleOwner) { entryList ->
valueView.text = entryList.joinToString(" ")
}
}
}
Im trying to pass data between two fragments but i have an error with arguments in execution when i launch fullFragment
i updated my code
Can you help me ?
architecture :
ListeFragment (sender) :
class ListeFragment : Fragment() {
companion object {
fun newInstance(s: String) = ListeFragment()
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View {
val layout = inflater.inflate(R.layout.liste_fragment, container, false)
val photo1 = layout.findViewById<ImageView>(R.id.imageButton1)
val model = ViewModelProviders.of(this).get(ListeViewModel::class.java)
imageButton1.setOnClickListener {
val newFragment = FullFragment()
val args = Bundle()
args.putString("key1", "data")
newFragment.arguments = args
Navigation.findNavController(imageButton1).navigate(R.id.versFullFragment);
}
FullFragment (receiver):
class FullFragment : Fragment() {
companion object {
fun newInstance() = FullFragment()
}
private lateinit var viewModel: FullViewModel
override fun onCreate( savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
var value1 = getArguments()?.getString("key1")
Log.v("value" , value1.toString())
Toast.makeText(context, value1.toString(), Toast.LENGTH_SHORT).show()
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val layout = inflater.inflate(R.layout.full_fragment, container, false)
return layout
}
I don't know what "newFragment.arguments = args" do because in FullFragment class I don't see any variable with that name, however you have to use "Fragment.setArguments(Bundle)" to set Fragment Arguments from the first one. Then in the Full you will have a correct result from "FullFragment.getArguments()" method.
PS: don't forget that the Context could be NULL in Fragment class and it should be handled in proper way.
I have a tablayout inside a fragment. The tab layout has 3 tabs. Which tab has a fragment.
And, in the first fragment I insert a string and add it to a viewModel MutableLiveData<ArrayList>> variable.
Then, I want to observe in the third fragment.
My main ViewModel:
class MainViewModel : ViewModel() {
val message = MutableLiveData<ArrayList<String>>(arrayListOf())
fun myMessage(msg: String) {
message.value?.add(msg)
}
}
Third Fragment:
class Fragment3 : Fragment() {
lateinit var model: MainViewModel
private lateinit var viewModel: MainViewModel
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val view= inflater.inflate(R.layout.fragment3_fragment, container, false)
model = activity?.let { ViewModelProvider(it).get(MainViewModel::class.java) }!!
model.message.observe(viewLifecycleOwner, Observer {
Log.e("aqui", "aqui$it")
})
return view
}
}
My first Fragment:
class Fragment1 : Fragment() {
lateinit var model: MainViewModel
private lateinit var viewModel: MainViewModel
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val view= inflater.inflate(R.layout.fragment1_fragment, container, false)
model = activity?.let { ViewModelProvider(it).get(MainViewModel::class.java) }!!
var btnTest= view.findViewById<Button>(R.id.btn_test)
btnTest.setOnClickListener {
model.myMessage(et_text.text.toString())
}
return view
}
}
When I open the Third fragment it observes as planned. When I come back to first Fragment and add more Strings to the array list, the third does not observes again, I don't know why.
First Observer:
My layout:
My observer only observes once.
You have to change the value of the live data instead of just adding an item to the already set list.
Change your function myMessage as:
fun myMessage(msg: String) {
val list = message.value
list.add(msg)
message.value = list
}
This will take your existing list then add your new item and then set the value of the live data so that the observe will be called.
I'm new to Kotlin and android development but i can't find why my program isn't working.
I'm trying to be able to communicate from my first fragment to his child, and testing it with a string but it won't display.
Thanks in advance for your help !!!
My first fragment :
class FirstFragment : Fragment() {
private lateinit var viewModel : Communicator
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_first, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
viewModel = activity?.run {
ViewModelProvider(this).get(Communicator::class.java) // .of supprimé
} ?: throw Exception("Invalid Activity")
viewModel.message.value = "test"
view.findViewById<Button>(R.id.button_stall_selection).setOnClickListener {
findNavController().navigate(R.id.action_FirstFragment_to_SecondFragment)
}
}
}
Here is my second :
class SecondFragment() : Fragment() {
private lateinit var viewModel :Communicator
private var msg: String? = ""
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_second, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
viewModel = activity?.run {
ViewModelProvider(this).get(Communicator::class.java) // .of deleted
} ?: throw Exception("Invalid Activity")
viewModel.message.observe(viewLifecycleOwner, Observer {
msg = viewModel.message.value
})
view.findViewById<TextView>(R.id.textView_1).text = msg
view.findViewById<Button>(R.id.button_second).setOnClickListener {
findNavController().navigate(R.id.action_SecondFragment_to_FirstFragment)
}
}
}
and finally here is the viewModel class i'm trying to use in order to communicate :
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel
class Communicator() : ViewModel(){
val message =MutableLiveData<String>()
fun setMsgCommunicator(msg:String){
message.setValue(msg)
}
}
In your FirstFragment, try to call viewModel.setMsgCommunicator("test") instead of directly calling viewModel.message.value = "test"
When the application starts, null is displayed.
I think that I am not correctly assigning a value to the TextView.
class MyFragment : Fragment() {
private lateinit var textView: TextView
companion object {
private val TEXT_FIELD = "text_field"
#JvmStatic
fun newInstance(text_field: Int) = MyFragment().apply {
arguments = Bundle().apply {
putInt(TEXT_FIELD, text_field)
}
}
}
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?): View? {
val view = inflater.inflate(R.layout.fragment_my, container, false)
textView = view!!.findViewById(R.id.text_view)
textView.text = "${arguments?.getInt(TEXT_FIELD)}"
return view
}
}
You have putInt in assignment but you do getString when trying to retrieve the value.